In recent years, hydraulic fracturing has become a significantly common and more cost efficient method of extracting natural gas from shales and tight formations. In the past, the downhole tools used have been constructed with a significant amount of metallic material such as aluminum or brass to construct a percentage of or all of the mandrel and other components. This construction requires significant drill time as metallic material is often difficult to drill. Accordingly, there is a need for downhole isolation tool construction that has the strength provided by metallic material, while using a smaller percentage of the metallic material.
Further, as non-metallic material has began to be utilized to construct downhole tools, there is a need for an downhole isolation tool that allows a user to alter the subassembly to form three or more different and separate configurations of the isolation tool without having to add metallic components such as brass, aluminum or other comparable metallic materials to the subassembly that would have to be drilled or milled from the wellbore.
Also, separate components have been needed to hold lower components of a tool in place and/or to provide a contact point for a setting component. Commonly referred to as a lock ring or load ring, this common downhole tool component has been utilized for many years. By eliminating the use of a lock ring, which typically contains metallic materials, there is less material to be drilled out from the well bore.
In addition, shear studs, shear rings, and/or shearable or partible mandrels have also been utilized throughout the industry to set downhole tools in the well bore. The use of shear studs would hamper any conversion of downhole tools due to the fact that these setting devices typically attach to a tool inside of a mandrel, meaning that any conversion would more than likely have to take place in the bottom of the tool. Bottom conversion would be unlikely or generally mean that the bottom tool component, commonly referred to as a shoe or lower guide, would have to be removed to make the conversion. Bottom conversion would also have a negative effect on how the zones isolate during drillout. The use of shearable or partible mandrels mean that the actual downhole tool separates, parts and/or actually breaks in two pieces.
Therefore, there is a need for a composite downhole isolation tool that can be easily converted from one configuration to another in a matter of minutes while in the field without having to add metallic components to the subassembly that would have to drilled or milled from the wellbore. There is also a need to be able to set a tool utilizing simpler and more cost efficient methods that do not require the use of shear studs, setting rods, shear rings, or partible or shearable mandrels. Such a tool would allow a user to purchase one down hole tool, easily and cheaply convert it into at least three different configurations, and set it in the wellbore using a more reliable and cost-efficient method. Accordingly, an invention that provides a downhole isolation tool that can be converted without adding metallic components or removing any subassembly components and can be set simply and economically, will lower the overall costs of hydraulic fracturing and have an important and positive impact in the industry.